text:
Why would a diverted airline flight return to its departure airport rather than land at the nearest one?
The Vueling flight VY2119 Barcelona-Malaga yesterday (see flightradar) got diverted 50 min into the flight. The nearest airport then was Valencia, but they chose to turn around and fly all the way back to the origin airport, even flying by another airport, Tarragona. Indeed, the whole flight takes regularly 1h40, they could well have flown all the way to Malaga and would  have spent the same amount of time in the air.
Why have they chosen to fly back? Wouldn't an emergency require landing in the nearest airport?

There's that time a British Airways 747 for London had a single engine failure at takeoff at LAX.  They diverted to Manchester.

@Harper-ReinstateMonica: yes, that example is more interesting than mine for sure. Linking: https://en.wikipedia.org/wiki/British_Airways_Flight_268

@Harper-ReinstateMonica Yeah, on the other hand, I'm not sure that that one was a great example of proper decision making...

@reirab nothing wrong with the decision making there - they could have diverted at any point if they had further issues, and both the CAA and the company had no issue with the pilots decision.  Ultimately, they only landed at Manchester because they weren’t sure they had access to the fuel in the outer wing tank due to the engine failure, and thus decided to divert to Manchester rather than continue to Heathrow - but in reality, they had access to that fuel and could have continued to LHR without issue.

@Moo The FAA apparently disagreed and fined them $25,000 for flying the aircraft in an unairworthy condition. I don't think range was so much the issue as that they flew across the Atlantic Ocean with a failed engine. You can't divert at just any point when you're flying over rural Canada, the Atlantic (or Arctic, as the case may be,) or Greenland. Diversion options are few and far between.

@reirab no, the FAA imposed the fine, BA appealed and the FAA dropped the case.  Given than the CAA found no issue with the pilots decision here, indeed citing in the report "As a 4-engined aircraft the B747 is designed and certificated to tolerate the loss of a second engine following an initial IFSD, without losing essential systems or necessary performance capabilities" and also "Thus, no evidence was found to show that the flight continuation posed a significant increase in risk" I think the pilots did just fine.

Report for anyone who wants to read it: https://assets.publishing.service.gov.uk/media/542302bfe5274a1317000bd7/Boeing_747-436__G-BNLG_06-06.pdf

@Moo The appeal was only over jurisdiction, not lack of merit.

@reirab and now you are nit picking.

@Moo Personally, I would consider pointing out the case being dropped when it was only dropped due to a question of jurisdiction to be more picking nits, but we can agree to disagree. Personally, I would consider any in-flight engine failure to be an emergency, at least on an airliner.

@reirab but it wasnt just dropped due to a question of jurisdiction, there was a question of ambiguity in the rules. From the WSJ: "British Airways said even if U.S. rules applied, they were ambiguous. The U.S. rules require pilots who lose an engine to land at the nearest suitable airport, but, British Airways noted, they make an exception for four-engine aircraft if the pilot decides flying onward is "just as safe as landing at the nearest suitable airport."".  The pilots chose to continue and the FAA chose to have an issue with that after the fact.

@Moo holy smoke yeah, that's not nit picking.  That's actually a pretty big deal legally.

@Harper-ReinstateMonica: I don't know. It seems the FAA has a point: IF you divert, you divert to the closest airport. Manchester was therefor the wrong airport to divert to. The nitpicking seems to be in the formal complaint, which was incorrectly worded.

@Harper-ReinstateMonica - wow. Great decision making. Remind me not to fly BA...

@MSalters they didn’t divert to Manchester because of the engine out, they diverted to Manchester because of higher fuel burn than expected due to stronger headwinds during the latter stages of the crossing.

It sounds like it was a non-emergency condition where it wasn't feasible to continue to destination but it wasn't imperative to land ASAP. Something like an anti-icing malfunction where you can't continue into icing conditions (all you need is visible moisture and temps close to freezing; clouds of any kind near or above the freezing level constitutes "technical icing conditions" and you may at minimum have to have working cowl anti-ice to fly through them).
The crew will often consult with airline Operations and Maintenance Control over a desired diversion airport.  Having decided not to proceed to destination, the next best choice is to go back to the departure airport, where passengers that originated at the departure airport can simply go home and return for a later flight.
The other major factor is maintenance related.  Maintenance Control will often ask the capt to divert to airport X because the resources are there, so if the departure airport was a maintenance base, that's another plus.

I'd change the order a bit. First consideration is "where can we get this fixed". If that is not an issue, then passenger considarations come at play. Dep airport might actually not be a well equipped one (and/or not a base for the airline) so even if passengers might prefer going back there, maintenance considerations override the needs of the pax. You just don't fly a broken plane to an airport with no maintenance, as you'd have to ferry the plane somewhere empty, or worse, you'd be stuck there and maintenance+parts would have to be flown there.

Depends on the fault.  But yeah Maintenance Control probably has the most influence depending on the airline.   A Jazz RJ capt I know told me once they almost always divert to where Maint Control tells them when they get a Caution Message enroute.

Unless of course you are Kenn Borek Air who seem to enjoy  repeated repairs in field :)

Another benefit to returning to your departure airport is that it probably saves on visa issues for the passengers. Landing in another country can be a hassle.

Not everyone getting on the plane at the departure airport lives in the departure city or even has a convenient place to stay in the departure city.

Of course not, but generally if you have to end up somewhere else from your destination, you're better off back at your departure point.

According to this article, the flight had a problem with one of the landing gear doors not properly closing. This caused too much fuel consumption to reach the destination airport. In such a case, an alternative landing airport is needed, but there is no urgency to land as soon as possible.
22 minutes after take-off the aircraft started its turn back to the departure airport, far from the halfway point between Barcelona and Malaga.
It is not uncommon for airlines to return to the departure airport instead of landing at the nearest airport in case of an in-flight failure. In this case, I can imagine that Vueling have more maintenance expertise at their biggest home-base Barcelona than at either Valencia or Tarragona.
They can repair the aircraft or make a replacement aircraft available to execute the flight with a few hours delay, or offer alternative flights to Malaga. Either solution will likely be quicker from Barcelona than from the other two cities.
For some passengers the trip to Malaga would no longer be needed after three hours delay (e.g. those that were flying there for a short meeting). For those passengers being back in Barcelona is better than being stuck in either Valencia or Tarragona.

authors: Bob Jarvis - Слава Україні


text:
Why can't an Airbus A330 dump fuel in an emergency?
It was reported recently that the Swiss flight LX18 from Zurich to New York had detected an engine issue shortly after take-off and decided to land back in Zurich.
Apparently, the Airbus A330-343 cannot just dump the fuel and, fully tanked, was too heavy to land safely, so it had to fly for 5 hours in a loop just to burn the excess kerosene.
Would it have been too complicated to implement a fuel draining mechanism?
What would have happened if they couldn't fly for 5 hours and had to emergency land right away? Wouldn't this inability to drop fuel be a safety hazard?

Closely related: Why doesn't the 737 have a fuel dump nozzle?

I would also guess that in densly populated Switzerland with its strict environmental protection rules such a thing as dropping fuel would be considered illegal and would result in a high penalty for the airline.

@Christoph: they could drop it in Germany, couldn't they? Jokes by side, when you drop fuel it dissipates, it's not as if people on the ground were bathed in jet fuel all of a sudden.

@Quora Feans: I'm no expert, just Swiss, but I think they can do it in the same way as I can drive somebody full speed to the next hospital if I have an ememgency (and I would), but still would loose my driving license in the process for several month and pay some thousands of Swiss francs for the court case and the penalty...

Just FWIW, according to another thread on airliners.net, fuel dump seems optional definitely on A330-200 and maybe on A330-300.

I'm a bit surprised that neither of the answers actually address the title question being asked at this time: they both go on about why an overweight landing should be avoided, but not why the A330 doesn't have the ability to dump fuel like some competing airliners.

@Christoph: Maybe not: https://www.rts.ch/play/radio/on-en-parle/audio/la-question-minute-lexces-de-vitesse-est-il-autorise-en-cas-durgence-medicale?id=8046656. In France you can try to call the "état de nécessité" (122-7 du Code Pénal)

Fuel dumping capability of twin-engine jets like the A330 is extra cost option that is fitted during aircraft construction.    Not all airlines order the capability.    Aircraft with more engines have more difficulty meeting FAR requirements (I don't recall which ones offhand) for climbing and landing near maximum structural takeoff weight, so are more often fitted with capability to dump fuel.

To supplement Jimmy's answer, if they had to land right away, they could have; it just would've resulted in an overweight landing being recorded, and which on most airliners triggers a special inspection of the landing gear and its attaching structure, and if nothing is permanently bent or cracked or broken, you are good to go.
An overweight landing in itself shouldn't result in damage unless the landing was hard, the overweight condition using up some of the structural safety margin, and if you know you are landing overweight you will take extra care to land smoothly.
Depending on the airplane, an overweight landing may apply a "penalty" so to speak, accelerating some inspection interval, or advancing a life limit on a structural component in the gear, or some other negative impact maintenance cost wise.  So there may be a significant incentive to avoid it from a long term cost perspective even if it means wasting 5 hours of fuel going round and round in a hold.
In the case mentioned, the crew would have consulted with the airline's Maintenance Control organization on the private company radio frequency to discuss whether to land overweight or not, and if there wasn't an urgent need to land, the Capt would have agreed with Maint Control and burn off the fuel to avoid the overweight landing and its ramifications.

On a commercial flight, is such a cost consideration (safety issues aside) a legitimate justification to keep passengers delayed for 5 hours?

Yes.  Same reason Maintenance Control will advise a crew to divert an airplane to airport X even though pax might prefer Y, because the airline has facilities at X.

I usually wonder, if they thought they were OK to fly in circles for 5 hours, why not fly towards your destination for the same 5 hours? They could even alter their route to always be within a reasonable distance of runway able to support them landing.

@SnakeDoc The route from Zurich to New York might not "always be within a reasonable distance of [a] runway" (where that distance is shorter than usual) and 5 hours into an altered route might have them landing on some ice patch in the North Atlantic where services and spare parts might be hard to find.

@WBT well ya, in that case sure, but what about trans-national, domestic, and continental flights? The US is large... but you often hear about something happening to the plane and it then circling for hours before landing at it's original location instead of just spending that time flying towards the destination.

It depends on the airline, and its financial situation as well.  Some airlines will eat costs to get pax there no matter what, others that are on the edge of bankruptcy all the time will shave pennies any way they can.  In the Regional industry in the US, once upon a time, operators would spend money upgrading airplanes with optional Service Bulletins if the improvement paid for itself within 5 years. By 2010,  they wouldn't touch it unless the payback was 1 year, and some won't do an SB unless there is an AD attached to it.  They simply didn't have the cash to spare.

Flying "toward" (but not actually to) your destination may be worse for passengers. Returning to the origin may mean returning to the airline's hub (Zurich) in this case, where they have facilities, staff, and are best positioned to arrange alternate flights and/or a new aircraft and crew. Taking passengers to another location may strand them somewhere without these resources (or worse, somewhere in the arctic). That's completely worth it if there's an emergency need to land there, but returning to the origin, especially if it's the airline's hub, is ultimately more convenient for everyone.

An overweight landing will often also add more stress on the tires (not unheard of that a few will blow up in this situation) and the brakes (which may heat it up quite a bit due to the additional energy to dissipate, to the point of becoming red hot, being a fire risk, and requiring the presence of fire engines to cool them down right after landing). An overweight landing is definitely possible if there's no other choice, but it's better if it can be avoided.

Have to agree with 0xdd this doesn't answer the question. The question is "Why doesn't the A330 have fuel dump capability?", not "what are the pros/cons of an overweight landing?". You've answered that question very well, it's just the wrong one.

I think the characterization that it's "too heavy to land safely" is erroneous; the fuel burning is probably out of circumspection and to allow for a better safety margin. The runway length may also be beyond the landing field length and/or the brake energy limit of the heavy weight, so decreasing weight would add to the safety if immediate return to land is not absolutely needed.
14CFR 25.473 requires that landing gear and supporting structures withstand a landing load at maximum takeoff weight at a contact speed of 6 ft/s. This is definitely reduced from the 10 ft/s design load for maximum landing weight, but is still larger than the typical landing speed of 2-4 ft/s. As I understand it, this requirement applies whether or not the aircraft has fuel dumping capability. Therefore, the aircraft has the immediate return to land capability, at least from a structures perspective.
So where does maximum landing weight and fuel dumping come in? On top of the distinction above, it is primarily a climb performance limitation as per 14CFR 25.1001: if the aircraft does not have a fuel dumping system, it must meet the all-engine-operating and one-engine-inoperative climb in the approach climb configuration at maximum takeoff weight. Otherwise, credit can be taken for maximum landing weight. So the design decision of whether incorporating a fuel jettisoning system or not comes down to this.

There may be some additional burdens, like EPA fines for dumping fuel in flight in the US. I don't recall reading anything in particular, but it seems like something one of several government agencies may have purview over.

Also consider the location. Assuming the a/c can do so, there would be no issue (apart from pollution) in dumping fuel over sea. But you want to spray jet-A all over Zurich? Plenty of ignition sources on the ground. Really not good.

Also jet fuel is quite hard to ignite, except in controlled conditions. For example dropping a lighted cigarette into a bucket of Jet-A has exactly the same effect as dropping it into a bucket of water.

Also, Zürich has 40km long lake right next to the city: Lake Zurich.

@bogl D Brooks was concerned about ignition sources, which, as ClobberXD and alephzero mentioned, isn't actually an issue. Nevertheless, fuel dumping is always done away from population centers, because the airline operators don't want to dump fuel on their customers.

@bogl People typically inhabit land. The sea, not so much.

And if you have a problem, how far away from any potential landing site should you go to dump fuel?

@alephzero there's perhaps an interesting question there: I've seen those youtube ATC videos where they get a plane out a ways from a city before dumping fuel and then vector traffic around the area for a while after. How close (in time, in distance) to the dump would another plane need to fly before it would actually be in danger?

@mbrig Feel free to ask that question by hitting the Ask Question button.

Jet fuel is basically diesel with some additives to improve fluid characteristics at low temperatures. Just like diesel, it can only be ignited at very high pressures and very high temperatures.

@forest This video shows how Diesel can be ignited when sprayed onto nothing more than a lit candle.

@PerlDuck: Indeed, if dumped jet fuel wasn't flammable, this airshow trick wouldn't be possible. But presumably that works only for a certain range of fuel-to-air ratios; by the time it reaches the ground from any reasonable altitude, I'd expect the fuel to have evaporated and dispersed enough that it cannot be ignited any more.

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sort: votes


text:
Can I use SkyDemon as a passenger on a commercial flight?
Could I use SkyDemon as a passenger on a commercial flight in an A320 or similar? Would doing so break any laws or safety regulations, assuming I set the callsign correctly?

SkyDemon on its own does not transmit your callsign or type. The reason you enter your aircraft details is for your own benefit of being able to store weight and balance info, fuel burn etc so some calculations can be done for you in the app itself.
So long as you follow the instructions of the crew, with regard to usage of personal electronic devices in this case, you will not be breaking any regulation.
For what its worth, I almost always have SkyDemon running when I'm departing or arriving back to the UK on a commercial flight, because yes I'm a geek :D and I can usually spot places I'm familiar with using a bit of location awareness.

Hey Jamie, well it's interesting you say that, because when I landed at Popham recently, they said "make sure you change your Sky Echo call sign as it doesn't match your aircraft"... Now I don't have a sky echo, but I did have Safesky and skydemon running. I wonder which one they "saw" me on...

@cloud Safesky for sure

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text:
Can you escape an aircraft through the lavatory?
In his book "Catch me if you Can", Frank Abagnale claims he evaded arrest by removing a panel in the lavatory of a VC10, climbing through it and hence escaping out of the (taxiing) aircraft through a hatch.
Could this actually have been done?
Plagiarism disclaimer: I found this question on another forum but didn't see a suitable answer there.

Depends if there is any pressurized space behind the lav, and if there are any hatches in the pressure hull within that space.  On most airliners I would say it's not plausible, but looking at a VC10 cutaway it looks like the pressure hull extends all the way back to the tail cone, to a small bulkhead under the rudder, and there is a hatch forward of that.  IF the mechanism can be worked from the inside, the hatch could be opened when taxiing because the hull is vented to atmosphere at that point.  It's possible that a panel in the aft most lav would expose a service hatch in the non-pressurized bulkhead where the engine support beam goes across, which would lead to the tail cone hatch.
Lot of ifs there, but from what I can see I wouldn't rule it out.
https://www.flickr.com/photos/27417638@N07/7408063162

If it's plausible, would that really only be if he got lucky and was aboard a VC10? Or would that possibly have worked in other common passenger aircraft?


text:
Is this statistic about the fatal accident rate correct?
This link says that:

fatal accidents occurred once every 200,000 flights in the 50s and 60s. Now, fatal accidents only occur once every two million flights

While many sources, including this one, agree that the average number of commercial flights per day is around 100,000.
If that is the case, then we should see a fatal accident every 20 days or so (2 million flights), but in 2017, there were no fatal incidents on commercial flight at all.
What is the explanation for this? Is it just that the first link is plain wrong?

The stat cited was "Now, fatal accidents only occur once every two million flights."   That quote is not specific about US only, nor about Commercial Flights only.   It is possible that there is a fatal incident in all flights, commercial and GA, world-wide, per 2 million flights.

The bit about "no fatalities on commercial flights" was for U.S. airlines. It was not only true of 2017, but also 2016, 2015, 2014, 2013, 2012, 2011, 2010, etc. The recent Southwest flight that resulted in 1 passenger death was the first passenger death on a mainline (not regional) U.S.-flagged airliner in scheduled passenger operations since 2001. A few fatal accidents have occurred on the regionals in that time, but not many (IIRC, 3 of them.)

@abelenky makes a good point. There are fatal aircraft accidents all the time in the US. Just yesterday a C130 crashed in Georgia killing 9 crew members. Surely, this type of fatality is counted in the link, but its not an airline so those 9 fatalities don't count when you talk about airline fatalities. Also, there are at least a couple hundred general aviation fatalities each year that  likely factor into the statistic.

@Devil07 Is that military?

I wonder what the figure is for car vehicle trips??  (Of course you can't compares since there's typically 1 human in a car and 100 in an airliner, and the typical trip length is different, but it would be interesting!)

@Fattie Well, if a car engine fails, you pull over. A single-engine plane loses an engine... it's gonna be tough

hi @Cloud - I'm not really sure what you mean.  the simple fact is there are X fatal car accidents each year, and Y car trips each year.  What are the two numbers, and hence the ratio.

@Fattie That's why one compares deaths per person-mile.

hi @DavidRicherby.  One can compare deaths per mile if one wishes.  One can also prepare statistics for deaths per flight (such as in the linked article); or deaths per flight (trip) by vehicle (as is very commonly analyzed).

This is potentially a good question for Skeptics.SE

The passage you're asking about is a paraphrase of something Boeing spokeswoman Julie O'Donnell said. If you follow the citation in the article, you can see exactly what she said, and when she said it.

"During the 1950s and 1960s, fatal accidents occurred about once every 200,000 flights," says Julie O’Donnell, a spokeswoman for Boeing. "Today, the worldwide safety record is more than 10 times better, with fatal accidents occurring less than once in every two million flights." [Emphasis added.]

O'Donnell is being quoted in 2014. According to the latest IATA safety fact sheet (published January 1, 2018), IATA measured a fatal accident rate of about one per 2.36 million flights in 2012, and one per 2.58 million flights in 2013. If I were rounding that down for a reporter in 2014, "less than once in every two million flights" is exactly what I'd say.
IATA counted 15 and 14 fatal accidents in 2012 and 2013, respectively. That's an average of one fatal accident every 25 days or so—just like you estimated. As @fooot pointed out in their answer, we've seen fewer fatal accidents in more recent years: an average of one every 30 days, 90 days, 40 days, and 60 days or so in 2014, 2015, 2016, and 2017, respectively.

Statistical postscript
I agree with your gut feeling that, if fatal aircraft accidents were happening at an average rate of one every 20 days, I'd be very surprised to see no fatal accidents at all last year. If fatal accidents were Poisson distributed in time, with a rate of one per 20 days, your chances of seeing no accidents in a year would be less than one in 80 million!
On the other hand, a year with no fatal large commercial passenger jet accidents is totally plausible, given the accident rate of one per 16 million flights that @fooot quotes. In 2017, that comes out to an average accident rate of less than one every 140 days—maybe a lot less, if large commercial passenger jet flights make up only a small fraction of all flights. If fatal accidents were Poisson distributed, with a rate of 1 per 140 days, your chances of seeing no fatal accidents in a year would be better than one in 14.

The statistic of 100,000 flights per day is a global one, and globally it is not true that there were no commercial airline fatalities in 2017. Per the Aviation Safety Network, there were 7 fatal incidents of commercial passenger aircraft in 2017. It's true that none of these were in the US, and most of these were smaller aircraft that do not get widely reported. If you only consider "large commercial passenger jets," the average is more like 1 in every 16 million flights. However, 2017 was a bit of an outlier. In 2016 there were 14 incidents, which is closer to the quoted average. In 2018 there have been 4 so far.
Fatal incidents are fairly random and will not exactly follow a certain average rate, not even over the course of a year. And with the total number being relatively low, it's even more prone to large fluctuations. The total trend in the accident rate has also been downwards, so we would expect more recent periods to be below average.

There have been 4 large commercial disasters this year? Source?

3 of them  Then one more  (and that doesn't count the single death in the Southwest flight which otherwise landed safely)

@Cloud I wasn't limiting it to large planes but it just so happens that they all qualify, the Axios link plus the Southwest accident.

@abelenky  65 and 66 deaths doesn't sound like a large commercial operation to me.

@abelenky I haven't been counting military crashes, or the numbers would be higher

Ok, maybe some miscommunication here. I was thinking along the lines of British Airways, Easyjet type airlines, not commuter planes with <100 people on board.

Sure... 99 people dying is no big deal.  Why should we concern ourselves with that?  (Colgan 3407 only had 45 passengers + 4 crew on board, but the result of that altered commercial pilot rules for the entire industry)

@abelenky No, of course even 1 death is not good and should be investigated. But I guess for selfish reasons (I only fly on Airbus or Boeing 737), that is all I am interested in.

Consider @abelenky's statement carefully. A single incident involving a small aircraft changed the rules for how large 737s should operate -- some causes affect all sizes of planes. It is unfortunate that we sometimes learn our mistakes only due to hindsight and only after fatalities. Therefore if it's for selfish reasons you should care about the cause of crash for all sizes of planes. It is actually quite rare that accidents are caused by aircraft type or sizes because when they happen you will hear about entire fleets being grounded

The link is not wrong but your math is a bit misguided. Just because an accident occurred on average every XXX,XXX flights does not mean that on flight XXX,XXX+1 there will be another accident, thats simply not how statistics work.
This also gets complicated due to the FAA's historical records and how the term accident has been used over the years. As regulations have gotten stricter and reporting has gotten more verbose we now have much greater insight into accident information than we did even 25 years ago. The FAA publishers a massive amount of info on the topic, you can find the real numbers for General Aviation here (for the last decade or so) and all accident reports are available here

While the term "accident" can be vague, "fatal" is not.  It's pretty straightforward to collect statistics on fatal aviation incidents.

+1 Statistics is usually counterintuitive to begin with. When we try to average and extrapolate over something as rare as "major airline crashes" it gets unreliable as well.

The problem is not so much the use of statistics, but rather misunderstanding what the statistics were describing. For U.S. airlines, the number is way less than 1 in 2,000,000 flights. For 2003-2017, it was around 3 in 146,000,000 for scheduled passenger flights and just plain 0 for mainline airliners in scheduled passenger service.

One can also review the NTSB records to see what the rates were like for more recent years to date. There is a 55MB file .XML that can be downloaded (and opened with what? I have no MS Office tools that will open it like an Excel spreadsheet or similar for sorting/manipulation). I'm pretty sure it's a big table.
https://www.ntsb.gov/_layouts/ntsb.aviation/index.aspx
Here's a row for example:
ROW PublicationDate="05/02/2018" ReportStatus="Preliminary" BroadPhaseOfFlight="" WeatherCondition="VMC" TotalUninjured="2" TotalMinorInjuries="" TotalSeriousInjuries="" TotalFatalInjuries="" AirCarrier="" PurposeOfFlight="Personal" Schedule="" FARDescription="Part 91: General Aviation" EngineType="" NumberOfEngines="1" AmateurBuilt="Yes" Model="KIS" Make="SENO LOUIS C SR" RegistrationNumber="N66SK" AircraftCategory="Airplane" AircraftDamage="Substantial" InjurySeverity="Non-Fatal" AirportName="EAGLE LAKE" AirportCode="ELA" Longitude="-96.321945" Latitude="29.600556" Country="United States" Location="Eagle Lake, TX" EventDate="04/29/2018" AccidentNumber="GAA18CA242" InvestigationType="Accident" EventId="20180430X21704"
The Table is accessible year by year and month by month here, seems a little easier to digest:
https://www.ntsb.gov/_layouts/ntsb.aviation/month.aspx

Hi, I'm a developer and we work with XML files, but you do not open them directly as an end-user. You can, however import the data into excel. Please see: https://support.office.com/en-ie/article/import-xml-data-6eca3906-d6c9-4f0d-b911-c736da817fa4

Cool, thanks.  So, we can sort and see 19 accidents, 21 injuries in 2017 and 20 accidents, 27 injuries (20 in just one accident) in 2016 for big iron, with no fatalities .


text:
Why are airplanes called ‘she’?
What is the reason that airplanes in English have a female gender?
Please illuminate the historical or scientific reason.

Much of aviation has a history in Nautical terms, lore... and law.
Ships were referred to as "she" perhaps for one of the following reasons

The latin word for Ship is "Navis" which is a feminine noun
Or perhaps mostly male ship owners would name their ships after/for their (invariably female) loved ones.
Ships were often dedicated to godesses, or women of significance in order to bestow on them good luck when seafaring

Some further reading and Why are ships always female? - english.se

Only slightly mentioned buried somewhere in there is an answer suggesting it's related to the female figureheads on many old ships. Older planes had women painted on them too sometimes, might be related?

Good answer.  I have just never heard anyone actually do this.  I have heard of this being a thing, but in 37 years around airplanes I can't remember a single time anyone referred to an airplane as female.

Aircraft, like ships, can evoke a fair amount of affection on the part of the aircrew, or ship's crew.
Until recently, most aircrew (outside of attendants) were male, just as most ship's crew are male. And most men would prefer to personify the subject of their affection as female, not male.
After all, you didn't see beefcake men as ship's figureheads, did you?

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text:
Can I overfly Canada without a passport?
Can an American pilot without a passport fly in Canadian airspace as long as they don't land in Canada?

What does FAA (a US agency) have to do with Canadian overflight regulations?

@ZeissIkon the pilot would be leaving and re-entering US airspace.

Even that is Customs and/or ICE, not FAA.

@ZeissIkon would this be better on Law SE?

Likely it's okay here since it's relevant mainly to aviation, you just need to fix the tags.  I see you've done that.  Should be answerable now.

Whether you are a pilot or not doesn't matter, passports and visas are not required to overfly the USA, Canada and most places in the world. A case in point, if you are flying from most of the continental USA to Alaska you will fly over Canada at some point but you are not required to bring a passport as it's considered a domestic flight.
It would still make sense to bring your passport though, if you do end up landing for one reason or another it will come in handy.

One doesn't even have to fly from the East coast to overfly Canada on the way to ANC, FAI or other Alaskan airports! Us Midwesterners get to go through Canadian airspace on our way up there, too. I've not brought my passport (as a paying passenger, not a pilot) on any of my trips to AK.

It's a good point @FreeMan, I've modified it to talk about the continental US.

Puts on pedant cap, gcmap.com doesn't show Canadian overflight for LAX-ANC. :D But this is accurate for about 99% of the US, so I'll just shut up now. ;)

If you please @FreeMan :)


text:
What are the three different altitudes shown in the Perlan II?
The Perlan II glider has two altitude indicators and an altimeter on the navi screen, each showing different altitudes:

How is each of the altimeters different? One indicator certainly shows MSL and the navi screen shows AGL but what does the other indicator with a yet different value show?

It's possible one indicator shows pressure altitude (flight level) while the other one shows absolute altitude above a geoid regardless of pressure (e.g. exactly 29,032 ft at Everest's altitude). But which is which?

The upper altitude is 66,560ft MSL. The middle altitude is 65,958ft AGL. Presumably, the terrain rises to 602ft MSL in that location.
The bottom altitude is 19,494m MSL, which converts to 63,956ft MSL. Note that this is GPS altitude, whereas the other two should be pressure altitude when up this high, so it is natural that they disagree by quite a bit.
Also, the two displays on the right show 66,569ft and 66,430ft. The former agrees with the MSL at the top of the main display, as I’d expect. The latter does not appear to be within tolerance and should be tested/calibrated, though perhaps the pilot just forgot to change it to pressure altitude.

I think so too, the 66569 ft number is probably the sea level pressure altitude as it's on the navi, while the 66430 ft number is an auxiliary altimeter to be trimmed to another pressure?


text:
US NOTAM Office disclaims foreign NOTAM accuracy or completeness?

United States NOTAM Office disclaims foreign NOTAM accuracy or completeness. Aircrews are highly encouraged to check host nation sources for supplementary NOTAM information. Source

What does mean exactly?

What that means is that the US NOTAM office does not have any jurisdiction or control over foreign generated NOTAMS, therefore they cannot vouch for their accuracy.


text:
What is the plane on the Home Bush Bay Funsaver EP cover?

Found this CD I had in 1997 and just bought it again as it got lost.
There is an aircraft which I cannot identify:

the sticker on the propeller leads to a propeller manifacturer called Avia
guess its a double engine plane with retractable landing gears
the picture on the CDs are invertet so I inverted the colors
guess it's a combustion engine, not a jet
the vent slots are pretty similar to Zlin planes but could not find a model which fits to the pictures

Solved: it's an Let L-200 Morava, thanks for your answers!

Is it possible you can adjust the first picture so that it is not upside down?

@RonBeyer I get the feeling the image is fine as it is and the engine was upside down in the original.

I was going to ask for album and artist, then I realized that it was on the CD label. Then I read "Home Bush" and thought "Is this Australian?" Then I looked at your user name. I get there. Eventually...

@FreeMan His user name says Austrian pilot, not Australian. :)

By the way @AustrianPilot, I think maybe you mean to say "piston engine" rather than "combustion engine." Jet engines are also combustion engines.

Hey, @reirab, did I tell you about that time I hopped that Lauda Air flight from Perth to Melbourne? ;) Sigh...

I submit the Let L-200 Morava.
https://en.wikipedia.org/wiki/Let_L-200_Morava
Engine Nacelles:

Nacelles and Nose Gear:

Nose gear Higher resolution:

I was just going to suggest a hint that AVIA is a Czech company. And someone has already traced the whole thing down!

I like how convenient this plane is.  When parking in a hangar you can just ram it into the back wall and the front tire will stop you.  What a time saver!


text:
How do AHRS systems meet the "gyroscopic" requirement of 14 cfr 91.205.d?
EDITED
Among the instruments listed as required for IFR operations in the US FAR is are various "gyroscopic" instruments, including those for the turn coordinator, attitude and heading. In modern avionics, though, there are no gyros. All the inertial sensing is done through some sort of non-spinning resonator (see https://en.wikipedia.org/wiki/Vibrating_structure_gyroscope). How are these things "gyroscopes" within the language of the FAR? Am I misunderstanding what the term means? I thought the "gyro" root meant "to turn in a circle" (as in "gyrate" or the making of the Greek sandwich), which is how heading/attitude/rate-of-turn devices all used to work. Obviously this is a nitpick since the point is to  sense  rotation. But then why does the FAR specify "gyroscopic" as a modifier for the various instruments?
ETA:
The origin of this question was a Sheppard Air test prep q referencing the FAR. Supposedly, all of these questions are on actual FAA exams. Here's another one, which in light of the comments I marked "B" for. But according to SA, the correct answer is "C". So (if SA is correct) the FAA seems to think here that a gyro is actually a spinning object.

(Also, thanks whoever downvoted this, while a People Magazine question about JFK Jr's IR training gets upvotes.)

I can’t cite a FAR, but it appears the FAA is accepting AHRS systems as “gyroscopic” if they provide the relevant functionality, regardless of whether they actually contain gyroscopes.

Remember, the "F" in FAR and CFR stands for federal.  The federal government doesn't move as quickly as industry...

Vibrating structure gyroscopes are (surprise) referred to as gyroscopes. So that would explain why they are called gyroscopic.

Related. This seems like semantics to me: laser ring gyros, MEMS etc. are still called "gyros" even though they have a totally different operating principle from traditional mechanical ones. It's likely that for engineers etc. "gyroscope" now simply means a device that provides certain functionality, regardless of how it operates. That might be more of an engineering or even English question than an aviation one, though!

Yeah, this was more a terminology question than anything else. It's still the case that if you just look up "gyroscope" online, you'll get a description of the spinning thing. And the term "gyroscopic effect" refers to rotating body rigidity of orientation. I guess with that context I'm just puzzled by the explicit use of the term in the CFR.

gyroscope: “[…] from Ancient Greek γῦρος (gûros, “circle”) and σκοπός (skopós, “watcher”).” Mind the second half of the word. It means, and always did, an instrument for detecting rotation, so it is rather obvious to apply it to those operating on different principle than a gimballed top.

In regulations, instruments are always defined functionally. They say what the instruments must measure, not how. Any actual implementation then has to be certified, but that certification concerns with accuracy of the instrument, its reliability and ability to detect its failure – because the pilot can only handle the failure if it is obvious to them – not it's principle. So anything that can locally (without external reference) measure attitude and rate of turn qualifies.
Note that the "gyro" root does mean “circle”, but don't forget the other half of the word:

[…] from Ancient Greek γῦρος (gûros, “circle”) and σκοπός (skopós, “watcher”).[1]:

It means, and always did, an instrument for observing rotation, though it was only used to describe one of the methods for doing so known to the person that coined the term (that person was Leon Foucault and the other method was obviously Foucault pendulum).

Understood, and I agree. This is really about terminology. (Which is a really annoying thing with the FAA exams.)
The thing is that the regs specifically mention “gyroscopic” instruments, then another question in the exam prep bank specifically identifies a gyro as a “spinning wheel or disk”. Just an old man grumbling over here...

@FosterBoondoggle: Ah, the wonders of the English language - "gyro" has more than one meaning, even within the FAA exams.


text:
KHAF runway 30 ODP in the works, appears to be missing a segment
Asked the FAA about this & they replied that the procedure has been redesigned since the one at the link was posted, that the old charts will be removed from the website, and that the newly designed procedure is currently in QC.
A long delayed ODP for runway 30 at KHAF can be found on the FAA website at this link. (Was supposed to be published in 2020, now scheduled for 2023.) The graphical portion is below. The text reads

TAKEOFF RWY 30: Climb to 1100, then climbing left turn on heading 150° and on PYE R-144 to HADLY, then on OSI R-255 to OSI VOR/DME. Cross OSI VOR/DME at or above 3500 before proceeding on course.

My questions are twofold. One is that the drawing indicates intercepting PYE R-144 from the left. This would be a hugely wide turn from 1100' off R30 at HAF. But even leaving that aside, and assuming they just drew it this way to reduce clutter, is it normal to not indicate on an ODP how you are supposed to intercept a radial? If you do a standard rate turn to 150 after climbing to 1100' you will end up well to the east of PYE R-144 on a parallel track (according to my sketch in Foreflight, which shows PYE R-144 having a bearing of 149 there) and never end up at HADLY. Of course this depends on the speed of the plane. But even at 200 knots (below the B shelf here) I estimate a 150 degree standard rate turn (from 300 left to 150) takes ~2 nm of linear distance, far less than the 5 nm or so between KHAF and PYE R-144. To make this work you really need to do something like "climbing left turn heading 190 to intercept PYE R-144". But you can't really tell that from the (misleading) diagram or the text.
ODPs weren't a big part of my IR training, so I'm wondering if this is common and you're just supposed to join the radial however you want to make the procedure work (i.e., using a steep enough intercept so that you join before HADLY).

Thanks for the update, but it would be better suited as an answer so everyone can see that this has, in fact been answered.

Asked the FAA about this & they replied that the procedure has been redesigned since the one at the link was posted, that the old charts will be removed from the website, and that the newly designed procedure is currently in QC.

In case anyone still cares, the SEEMS departure now exists and for piston singles it stinks. Takes you 6 miles offshore. I got assigned it the other day when I said I was departing 30. In the future I'll stick to departing off 12 when I need IFR to get out.


text:
Does the FAA's restriction on adjustment of attitude indicators (14 CFR 23.1303(f)) still apply to aircraft today?
The GA planes I fly (with a club) have Garmin G5 PFDs. On these, the horizon/attitude indicator shows a few degrees pitch-up when in level flight. They're adjusted to indicate level on the ground based on the aircrafts' centerline, but in-flight changes in speed or W&B of course shift the actual attitude for level flight. This is kind of annoying when trying to develop instrument skills. The reason for this limitation for certificated aircraft (per Garmin) is an FAA regulation (14 CFR 23.1303(f)):

When an attitude display is installed, the instrument design must not provide any means, accessible to
the flightcrew, of adjusting the relative positions of the attitude reference symbol and the horizon line beyond that necessary for parallax correction.

Never mind the "why" of this (it seems odd, but what do I know...). The above text is from a 2017 version of the code. (Actually published in 2011, per the GPO.) When I go looking for current versions on .gov sites, they don't exist. On the current gov eCFR website, I get this response when looking for that section:

The content you requested is no longer in the eCFR. It was removed on 2017-08-30, but the prior content can be viewed here.

There is a similar section of federal regs for transport category aircraft (25.1303) but it has no subpart (f) and says only that a bank and pitch instrument is required.
With all that windup, my question is: does this restriction on attitude indicators still exist? I cannot find a current version of the regs containing this restriction.

Closely related, perhaps even a dupe if your core question is about why 23.1303 is gone.

You indicate learning instrument skills, have you ever flown in real full IMC or all simulated/hood time?(it's not the same) Manually adjusting it in flight would defeat the whole purpose of a gyroscopic instrument. If the nose is slightly up it should show the nose is slightly up, it does not matter that you are in level cruise. If the pitch is up higher than normal in steady conditions that is an indication of something wrong, like slow airspeed(and a faulty ASI) There is no reason to just adjust that away and ignore it.

What the current rule is doesn't really matter relative to the G5. The G5 was certificated via an AML STC. The rules in place when the application for the STC was made were the applicable rules. The STC remains valid even if the rules change unless the FAA specifically includes in the new rule that previously issued certificates are rescinded (which is pretty rare.)
So as long as Garmin keeps building the G5, it has to be built to the existing design. If they make a major change to the design or start a new design, it would have to be to the current rules. Minor changes to a product can be made without a change to certification basis.
With the new 'performance based' rules, it would be difficult to predict result of the certification process for a new product. It's the manufacturer's responsibility to design the product and show that it meets the rules.

My understanding is that the G5 for “experimental” aircraft doesn’t carry the limitation on adjusting the horizon indicator. So they already have these things as part of their production process (presumably differing only in software). Are you saying that if they wanted to deviate in even this seemingly small way from the STC they’d have to go through a new certification? (It would sure be nice to be able to adjust the thing in flight.)

They would have to amend the STC at a minimum. Even with the new rules, they would still have to address the function in their system safety analysis (SSA). They old rule existed to address some perceived hazard, so you couldn't just say it isn't a concern because it isn't in the new rules. The new rules still require you to address the hazards, they just don't tell you how to do it. In any case it isn't a small impact. It affects manufacturer's that buy the G5 as they'll have to amend their TCs, spare parts substitutions, documentation, etc. And it's unlikely to affect sales.

The FAA rewrote 14 CFR Part 23 entirely at the end of 2016, and those changes went into effect August 30, 2017. You can find a discussion of the changes made in the Federal Register at 81 FR 96572. The current standards are in the new 14 CFR Part 23, which I find easiest to browse on ecfr.gov.
Based on my reading (I am not a lawyer, I am not your lawyer, and I'm not an aircraft mechanic), it looks like the restriction you asked about was deleted. This seems to comport with the general purpose of the Part 23 overhaul, which replaced "prescriptive design requirements with performance-based airworthiness standards." (Quoting the summary of 81 FR 96572.)


text:
Flying an RNAV SID with instructions to intercept a course to a waypoint
Looking at the OZZIE FOUR departure off APC (first page shown) the instructions are, e.g.,

TAKEOFF RUNWAY 19L: Climb on heading 186° to intercept course 269° to KLARK, then on track 342° to FIRTO at or above 2700, then on track 350° to OZIEE at or above 6000, thence...

I know the first step can be done with GPS equipment by using the OBS setting with KLARK as the reference, but is this what the design intends? I've never seen the OBS mode used for anything except runway centerlines and the like. Using it for IFR nav relative to a GPS waypoint never came up in training. I would have expected the procedure to include a flyby waypoint where the 89° radial off KLARK meets the 186° radial off APC, which would make the first turn work like any other. How do people program & fly something like this in practice? (Also - more of a TERPS question - why are the courses to KLARK off 19R/L not the same & likewise for 1R/L first turns?)
ETA: this is not in reference to any specific equipment beyond RNAV capability. I'm just puzzled by the specificity of the courses to the first waypoint, and the SID charting showing turns at specific points in space not associated with a waypoint. It says specifically "intercept course 269 to KLARK". I can use OBS mode to do this, but is that what's intended?

"How do people program & fly" will obviously depend on the aircraft and the installed equipment. Can you narrow that down a bit?

See edits - I'm asking about the specificity of "intercept course 269 to KLARK". The GTN6xx/7xx series can certainly do this with OBS mode, but that seems like a non-standard use case. I used "radial" which I guess technically applies only to VORs, but I'm just referring to the course being specified relative to a waypoint.

Related: What is the operational advantage of starting an RNAV SID with a VI-CF leg combination? What you describe here is VI (heading to intercept) followed by CF (course to fix).

@Bianfable, thanks, yes seems related, though that post's question is a bit different. The SID referenced in that post no longer exists at DEN, but the CHUWY has similar narrative for 35L/R departures. Why not just "reaching 7000 climbing left turn direct CAAZZ" or something similar rather than "intercept course 338"?

@757toga - yes, I understand it can be flown in this hybrid VOR-like using a "radial" (GPS in OBS mode) then waypoint-to-waypoint. I am just puzzled by the absence of a flyby waypoint at the intersection of the KLARK course and the runway heading to define the turn, which makes me think I misunderstand the intention of the design. Other RNAV SIDs I've used/looked at before are defined by turns, altitudes & waypoints with never a need to use OBS mode to intercept a course.

Yes, you should be intercepting the specified "radial" to KLARK just as if it was a VOR station. This is a relatively common way to begin a SID.

"Using it for IFR nav relative to a GPS waypoint never came up in training."  What did they teach you about GPS navigation in training then?!  (IFR vs VFR is really the same...)

@MichaelHall Uh, lots of things. "It" in that sentence referred to defining a track off a GPS waypoint with OBS mode. It's kind of an obvious thing to do (as I noted in my post) but I'd never before seen a procedure where you would have to switch between OBS mode and GPS point-to-point mode in the middle.

I understand puzzlement over there not being a waypoint at the almost 90 degree dogleg from takeoff course to KLARK, but I'm not sure what you mean by "you would have to switch"...  Have you actually loaded this procedure to see what it looks like in map mode?

Depending on your aircraft equipment, when you load a SID, as STAR, or any route, (whether manually or from a database) all the legs will simply be there.  You may review them in map mode if you have it.  In fact it is encouraged, and may even be required, that you scale out on the display and review the general shape of the procedure against what the chart shows to verify that the points are correct.
Once loaded, you can fly in either map mode, or OBS.  Either way, your deviation left or right of course will be show on the CDI.  Additionally, the active leg to your next waypoint will be displayed as a magenta line.  So even without a CDI, in map mode you simply put your aircraft symbol on the line and follow it.

That's correct (I just tested it in a GTN750) but it seems like an odd design. The 750 appears to put in an "uncharted" waypoint at the intersection of the two courses and do a standard flyby turn past it.  I am still puzzled by what the benefit is here to not putting in an explicit waypoint and why it's done this way.

@FosterBoondoggle, I typed my last comment above before I read this...  I get that it seems odd, but as long as the "uncharted waypoint" leads you to fly the procedure as published it must have passed muster by those who approve such things.

The "uncharted waypoint" is known as a 'Floating Waypoint' in the FMS. The reason is that it isn't at a fixed point. The reason it isn't fixed is that the initial departure leg is a VI leg (heading to intercept). Heading legs don't correct for wind so when you depart "Fly runway heading" your course will drift left or right depending on the wind. That will change the point where you intercept the CF leg. As you fly the leg, the FMS (or GPS navigator) will be using your actual track to predict the intercept and generate the fly-by turn at the appropriate point.

@Gerry - that is a really great observation. Thanks. I fly bugsmashers, not big iron, so I'm not familiar with a lot of the  subtleties of SIDs & STARs, particularly that apply primarily to jets.


text:
When do the LNAV and VNAV NPS pointers appear in the PFD of a B737NG?
I am pretty sure the LNAV NPS pointer should appear from after takeoff, if LNAV is armed.
But I am not sure about the VNAV NPS pointer. A VNAV climb is based on Speed, not Path, so I assume there is no NPS Pointer visible during a VNAV Climb.
When will it first come on? Once cruise altitude is reached? What happens if one has to level-off before reaching his CRZ FL? Will the NPS pointer appear at that time?

Interesting question; offhand I want to say, when there is a defined vertical path - so upon reaching CRZ altitude... but I'll have to check that. Leveling in ALT HOLD doesn't create a vertical path, so that wouldn't do it; leveling at a crossing altitude on a SID, probably would. I'll try to remember to notice when they appear on my next trip & give you a real answer.

Checked it on a departure & at cruise - no NPS while in VNAV PATH in either of those instances. Then went to the manual, which says that the vertical NPS is only active after Top of Descent. So, there it is.

The lateral NPS will be present if there is a defined LNAV track active, and the APPROACH mode (i.e. to track an ILS) is not active. The vertical NPS is inhibited until the FMC-computed Top-Of-Descent point, so it won't be present during an intermediate level-off during an RNAV departure. It's also inhibited after GS Capture, since the ILS glideslope is then primary & having the NPS would be distracting & unhelpful.

Thanks for clarification, the manuals I have don't mention the bit about the vertical NPS being inhibited until the FMC-computed TOD. They are old so it may have been added later.

The manual that I have says that

lateral NPS deviation scale represents current FMC lateral RNP.
vertical NPS deviation scale represents current FMC vertical RNP.
the NPS pointers are displayed if an approach mode is not engaged,
and either TO/GA, LNAV or any VNAV mode is engaged.

The flight management manual says
Vertical Actual Navigation Performance
[Option - FMC U10.5 and later with vertical RNP enabled]
Vertical Actual Navigation Performance(VANP) is the FMC's estimate of the quality of its altitude determination. It is shown on RNP PROGRESS page 4/4. VANP represents the estimated maximum altitude error with 99.7% probability. That is, the FMC is 99.7% certain that the airplane's actual altitude lies within a vertical band equal to plus or minus the ANP value.  The lower the VANP value, the more confident the  FMC is of its altitude estimate.
Note: VANP is calculated from the baro-corrected altitude provided by the Air Data System. The pilot must set the baro setting reported by ATIS or provided in the approach clearance for the 99.7% confidence level to be valid.
Vertical Required Navigation Performance
[Option - FMC U10.5 and later with vertical RNP enabled]
The FMC uses 400 feet as a default Vertical Required Navigation Performance (VRNP) value for oceanic, en-route, and terminal phases of the flight.
Just as a matter of interest there is an interesting document by Boeing here (it doesn't answer the question in its entirety though).

The LNAV deviation scale is active anytime LNAV is in the engaged FD
or autopilot mode.

"the NPS pointers are displayed if an approach mode is not engaged, and either TO/GA, LNAV or any VNAV mode is engaged." In such a case I wonder what vertical "deviation" does the pointer show during a VNAV climb. The climb is not a fixed PATH, it is defined by Speed. Does the pointer indicate the deviation from the target speed?

@StamatisVellis It should show the FMC's estimate of the quality of its altitude determination, according to the information I added.

The lateral NPS shows if you're in HDG SEL + ALT HOLD... nice to see how far off your course this vector is taking you.


text:
How do pilots manage their flight times?
When flying double-digit hour flights, such as 13 hours from Chicago to South Korea or 18 hours from Singapore to Newark, New Jersey, everyone on the plane, including the pilots, will most likely experience jet lag, as the passengers will experience "nighttime" at some point and become sleepy. Since there are two pilots, the pilot and the copilot, how do they manage their time? Does the copilot start flying the plane when the pilot rests, or vice versa? Or do both stay awake for a grueling 18 hours? Or do they rely on autopilot?

We have a couple of questions already that talk about this: here, here. Do they help?

They do in a way.

Airlines are required to have extra pilots on long flights so that pilots can take rest breaks.
A typical 18 hour flight from New York to Singapore will have four pilots. The pilots will divide the rest breaks so that there is always two pilots in the flight deck at the controls, and two pilots in a crew rest facility. Most crew rest areas will have beds or bunks to sleep in.
Typically all four pilots are in the flight deck from takeoff to about 10,000' and then again from 10,000' to landing. The cruise portion of the flight be divided so that each pilot gets an equal amount of rest. Various airlines will differ on how this is done.
Usually two pilots will be paired to take the same rest breaks so that they don't disturb anyone when they enter or leave the crew rest area. For example many airlines will divide a 16 hour cruise portion of the flight so that the paired pilots each get two 4 hour breaks. Some airlines will divide the time so that there is one 8 hour rest period instead of two 4 hours rest periods.


text:
What about a Plane-Train?
The Shanghai Maglev Train's max speed is 267 mph. Could a plane be made to follow a rail, surface area provided, if not an existing rail to travel along? How much faster could the heavily modified train/plane travel?
The plane is "on rail, not touching the track while following it, not over water but over a track made of concrete" or less.
Another way to ask, is how much would a very large cruise missile shaped vehicle benefit from using ground effect (possibly using curved surface area or rail to follow) verses not? Because the the rail is not directly supporting the wight of the vehicle, at least directly, how sturdy would that rail need to be? When done over water, the water is displaced by the air pressure under the ground effect plane.

I would think that if you are going to rely on the infrastructure of a rail system you might as well get rid of the drag of the wings.  267 is plenty fast, if you want faster go in an airplane.  I just don't see any advantages to the sort of hybrid you have loosely described.  But go ahead, convince me!  ;)

When I first read the quesiton, I tought you wanted to revive the aerotrain, but then I realize you just want to make an hovercraft or a GEV. I fail to understand how different from an hovercraft your vehicle would be.

So, you want to take a mode of transport that has the fundamental property that it stays on the ground and combine it with another mode of transport whose fundamental property is that is does not stay on the ground. I think we can see why this idea hasn't made progress before.

The newest train under construction in Japan will reach approx 375 mph (603 kph).

If the vehicle must follow tracks, then it is a train, regardless of whether it is in contact with the track or hovering a few inches above it. Planes, even ones that can only fly in ground effect, do not have tracks.

"How sturdy would that rail need to be?" If it's a "cruise missile shaped vehicle in ground effect" then it doesn't need a rail at all because it's not touching the ground when moving, so the answer to that part is "tissue paper will suffice". I'm more than a bit confused by your proposal, could you expand on your question to give a better idea of what you're after?

@FreeMan I updated it. Water or not the surface area will still take some of weight of the plane from the air cushion but how much in comparison to a vehicles weight directly applied to the ground through physical contact..

@StephenS Not yet they don't. It is still a plane if it is dependent on air to travel as a ground effect plane does, it also depends on a relatively flat surface, and on land it would need to be a track. The plane could be magnetically driven externally not to need an engine, like a rail-gun and the ground effect plane would be the bullet.

@Justintimeforfun Given your last edits, I think you should also emphasize how your vehicle differ from the aerotrain (on rail, not touching the track while following it, not over water but over a track made of concrete)

@ManuH how is that?

Are you asking about ground effect trains?

@Justintimeforfun did you read the content linked in comments (not only mine)?

@TerranSwett no and yes but more towards just modifying a plane to behave like a train. With the ability to pull up if needed.

The first issue with airplanes is they are stupendously, freakishly light.  Any random American freight diesel locomotive weighs more than a 747-400.  Trains rely on this mass to provide the downforce to keep them engaged to the railhead.
So your vehicle would need to do something to replace this downforce; for instance have a tubular or I-beam rail which allows the train to grab the bottom of the rail; expect switches and special work to be complicated at that point, shifting an entire track instead of just small parts of it.
So while unloading weight off the rail only makes matters worse for track design, you're also paying for that lift with induced drag. In other words you're using a great deal more fuel (or electricity) to unload weight off the rail, when the rail really doesn't mind bearing weight.
In fact from an aviation perspective, the "induced drag" on a train can be approximated to zero, thanks to Mr. Babbitt (Mr. Timken's idea is worse for drag but better for reliability).
That's why good ole fashioned railroad just keeps winning the high-speed race (or coming too close to matter). The exact TGV train that ran 357 mph could be dropped onto a NYC subway branch in Brooklyn, interchange onto LIRR, come into Penn Station and the Amtrak Corridor, through the freight rail system to Detroit and run on Woodward Avenue Q-line, then to Long Beach CA and run on the Blue Line.  The only thing I'm arm-waving is power supply, and curve and platform clearances on NYCTA.  In fact, in 1993 Amtrak dragged an X2000 and ICE high-speed trainset all over America behind diesels. No wheel modification needed.
So while your idea has merit... once you get out the sharp pencil and really start optimizing for performance, you will find it best to forget wings and load full weight on the rail, and further, to optimize for Plain Old Railroad Track so you can just use existing rails to get downtown.  Going with a wack-a-doodle guideway doesn't buy you much, and makes getting downtown a mega-project of biblical proportion  all its own. Here:

The city of Victorville was selected as the location for the westernmost terminal since extending the train line farther into the Los Angeles basin through the Cajon Pass would be prohibitively expensive.

/facepalm... Cajon Pass is not a challenging hill for HSR. If they can't even handle that, they sure aren't getting into L.A. proper where all the connecting trains are.  And L.A. is a piece of cake compared to a dense, old city like Paris or even Boston.  This: This is the folly of a wack-a-doodle guideway.  They finally retreated from that to a standard railroad design, so they could come downtown on shared rails.

I am not worried about max efficiency as far as the vehicle, so much as max efficiency for the speed of it; to have a plane to travel like a train to achieve higher speeds verses normal cargo or passenger flight or train ride. Less efficient than a train, but more efficient than normal cargo flight.

If I could make my question read like your answer. Great work!

To elaborate on your last point, if you have a vehicle with wings following the railway, you need a much wider right of way.  You also need to rebuild all multiple track sections of your railroad to provide sufficient clearance for vehicles going in opposite directions, and you have to worry about intruding cows, deer, humans, &c being struck by the wings.  As pointed out, a diesel locomotive is a LOT sturdier than an airplane wing.


text:
Flying in V formation with multiple planes
Logistically choreographed using air-traffic controllers to pair like planes headed in the same direction or by scheduling flights together, how much fuel could be saved pairing planes to fly in a tight V formation throughout a fleet?
Maybe an autopilot could both keep a heading while maintaining an optimal position with in the formation; or in other words, Auto-formation.

Are you asking about airliners flying in groups to save airspace (in which case you should title the question "how much money would be saved by flying airliners in formation to save airspace?"). In that case would you allow formation to break and reform with other airliners? Or are you asking about effect of formation flying on overall drag ?

I think he has the flock of geese in mind.  A small jet like an RJ could fly in the upwash forward and above the leading edge of a 747 and probably reduce its thrust significantly to stay in position, but who would want to ride in the thing.

@JohnK if you are right, there are already highly related questions (if not dupe): Why isn't the V flight formation being used for commercial purposes?, How do planes benefit from flying in formation?, How much can a plane benefit from another planes wake?

The US Air Force has experimented with it and it seems they've built the option into their auto-pilot programs.


text:
Has any pilot successfully flown through a hurricane with a single-engine prop plane?
Has any pilot successfully flown or could a pilot crab through a hurricane using a plane such as a Cessna or bi-plane?
Would acrobatic planes work better because of their nimble agility and high power-to-weight ratio, or would heavier aircraft be more stable?
Are there any prop singles that would be particularly well suited?

I don't have a specific make and model for you, but I'd look at something that has good icing systems.  Prop, wing, and empennage deice.  Pitot heat, carb heat (for piston engines) and windshield heat.  You're going to get in to icing if you're trying to penetrate an eyewall.  Beyond that, something that's rated for high positive and negative g's.  As a comparison, the P-3's that NOAA flies through hurricanes were designed for 3 g's, which really isn't that much.  I have it on good authority that they've seen 5 g's while in extreme turbulence.

Something like the T-6 would have the power & the ability to handle the g forces; don't know how it'd handle icing. You'd want a radar pod on the wing of whatever you picked; that'd be an after-market upgrade on a T-6.

@Justintimeforfun, I think it depends on the altitude.  I watched a few videos of the NOAA flights and I could tell from the switch position they didn't have their engine anti-ice on.  I'm pretty sure they stay relatively low, like below 10,000' so it would be warmer.  Other extreme weather though, you'd definitely want it.  I've gone through some heavy weather where we built up so much ice so quickly that we couldn't hold altitude.

related: When is turbulence most dangerous to an aircraft? and How do pilots clear an aircraft to fly through a hurricane?

A CFI friend of mine once entered a red cell over Florida in a Cessna 182, which he described as “the scariest f*cking thing I’ve ever been through.”  He described it as his entire field of view went a dark steel grey and all hell broke loose.

Flying through a thunderstorm is easily the most terrifying thing I've ever experienced.  It is not fun.  0/10, would not recommend.

There are three separate questions here that should be split up.


text:
What action should two planes on a collision course take?
What are the various types of procedures for two aircraft on a collision course?

head on, as the answer describes, or at an angle? are they the same class? which airspace?

@Justintimeforfun At what angle are the two aircraft approaching each other? Which Wake Turbulence Category are they in? In which Airspace Class are they flying?

@Bianfable to narrow the field, lets say USA or international airspace

FULL RIGHT RUDDER!!  Oh wait, that's for ships.

USA is not an airspace. Is it class A,B,C,D,E, or?

@Federico, actually FAA knows what is the US airspace, and expects the same from pilots, cf. "Entering, Exiting and Flying in United States Airspace"

@mins sure, but has no relevance on this question, since the answer mostly depends on the class, not the country. but ok, now this is a duplicate of a question that specifies VFR.

14 CFR 91.113(e):

Approaching head-on. When aircraft are approaching each other head-on, or nearly so, each pilot of each aircraft shall alter course
to the right.

There are also directions in 91.113 for right of way if the two aircraft are converging, overtaking or landing. I don’t know if you also consider those a “collision course” or not.


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The slowest to fastest ratio plane
What fixed wing, and motor, plane or jet, has the largest range between its minimum and its maximum airspeed by which it can safely fly for prolonged periods?

Related: https://aviation.stackexchange.com/questions/65780/would-a-two-seat-light-fixed-wing-aircraft-with-a-landing-speed-of-20-knots-and?rq=1

"Speed" is an ambiguous word when it comes to aircraft. Can we assume you're asking about true airspeed?

@Pondlife airspeed.

The question title asks for speed ratio (i.e. vmax/vmin) , the body asks for speed range (i.e. vmax - vmin). What do you want? The winner of the ratio contest will have a very low minimum speed, the winner of the range contest will have very high maximum speed.

@qqjkztd -- positive aoa does not require downward pointing thrust vector (or upward pointing thrust vector for that matter)

What is a "prolonged period"? The F-35 can hover in flight, and has a top speed of mach 1.6 (1066 knots)...

Even notwithstanding the F-35, anything with a TWR > 1 can, to some degree or another, do this.

I'd love to reopen this, but... not until the disconnect between "range" and "ratio" is resolved, the upper end being in TAS or IAS is specified, and VTOLs + gliders (and the Space Shuttle) being clearly ruled in or out. Until then, "needs clarity" remains the problem.

The radio-controlled model sailplane that recently exceeded 540 mph while dynamic soaring has to be a contender.  Minimum speed in this flight (immediately after launch) may have been as low as 10 mph, which probably could have been sustained by staying on the front side of the ridge.
Link to You Tube video--

Though any plane capable of routine flight at 0 mph would automatically win I suppose-- e.g. pretty much any hang glider or sailplane given the right conditions.
Or did you mean airspeed?  The radio-controlled sailplane in the video may well be one of the top contenders.

I admit it, having a little fun with opening up the box on what the meaning of "prolonged periods" might be, and a few other possible issues with the original question-- but the wind can likely blow longer than the typical fuel payload will last--!

The highest range of speeds will basically match up with a list of highest top speeds... take ~200 knots off of the top speed of the SR-71, and you probably have your answer. Or if the question is for currently flying jets, unless your #1 and #2 have top speeds so close that the delta in their landing speeds is greater than the delta in their max speeds, #1 is still first, #2 is second, and so on.
As for ratio, if VTOL jets aren't ruled out by the "fixed wing and motor" constraint (and actually, the nozzles pivot, not the motor, in most cases), you have to deal with an infinite ratio for a min speed of zero.
The dynamic soaring answer is inventive (and that video is amazing), and nothing else is likely to touch a 54X ratio (!!!), but the "and motor" constraint probably rules that one out too.
Even with VTOL ruled out, lowest landing speed is probably going to trump everything else; the garden-variety STOL single-engine prop with a range of 30-150 gets a ratio of 5x without even trying; the number of jets that land at 100 and reach 500 knots indicated is awfully small.
Oh, and for one more complication, are we talking KIAS or KTAS at the high end?  That can make a difference too!

I actually misread or mis-interpreted the question to be asking about "ratio" rather than "range" -- some parts of my answer make more sense with that in mind. Since the question says "range", this is a better answer -- except that the title says "ratio".  Really we should have asked for the question+title to be clarified/ improved before offering any answers...

The Space Shuttle (or "Space Transportation System (STS)") reportedly re-entered the atmosphere from low Earth orbit at about 17,500 mph, and touched down as low as 214 mph, for a ratio of 81.77.
https://www.nasa.gov/mission_pages/shuttle/launch/landing101.html

Not sure the full speed range would count here.  Until the lift-to-drag ratio gets above 1, the Shuttle can't be said to have been flying; at most, it would have been falling with style.

@Mark  Not to mention that the shuttle wasn't generally powered on the way down, so not really any more of a contender than that model glider.

@MikeBrockington How about on the way up? It's powered then, its thrust vector points straight backwards, and it starts flying with a speed just above zero, while ending up at orbital velocity. :) Of course, if it weren't for the "plane" constraint, then it still wouldn't win, due to other vehicles having exceeded escape velocity.

@reirab Don't think it counts as an aeroplane on the way up - 99.9% ballistic, if not 100%, so not really 'flying', is it?

@MikeBrockington I mean, it's still an airplane... just one that happens to not be using its wings to generate lift at the time. :) Similar to a fighter or aerobatic plane with TWR > 1 standing on its tail or accelerating straight up.


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Are Foward Swept Wings for a Rear Propeller Airplane Feasible?
Would going with a forward swept wing design, with the same cord and length of the "A Wing", bring more air the the propeller and tail to increase range, power, or stability?
Consider the material available today to save additional weight needed to add torsional strength for this wing.
The 1970s, BD-5A can get 1200 miles on the original (A Wing) airfoil/wings. It is known for being unforgiving, stalling often on landings. The airfoil has had some design changes to make it more stable using the "B Wing" at the cost of 1/4th of the mileage. The wings are interchangeable in 15 minutes.

The air doesn't flow along the wing quite like that. An airplane with a pusher prop wouldn't know the difference. Plus significant forward sweep requires a lot of extra torsional stiffness, hence weight. And you only do sweep in the first place for transonic performance. You just don't see swept wings more than a few degrees in subsonic a/c. So there's really no point.

@JohnK Consider the material available today to save additional weight needed to add torsional strength for this wing. Would you say there would be zero benefits?

For subsonic there isn't really any point in sweep. Airliners have sweep b/c they are transonic.


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How to calculate take-off and landing distances for a light plane?
I cannot find a generic takeoff chart for the 850 lbs BD-5B Micro-plane. How can I find, generate, or calculate the takeoff and landing distances needed? I did find this chart below and included the specifications. Please provide an example I can follow and learn from.

That is definitely not an ultralight!

@quietflyer what would you call it?

I'd call it fun!

@Justintimeforfun At least in the US, an ultralight must be less than 254 lbs. and carry 5 gallons or less of fuel. Since this plane has a gross weight of 850 lbs. and carries 26 gal. of fuel, it can't be an ultralight.

You need the values of at least thrust, weight wing surface, density and maximum $C_l$, obviously all at takeoff. I think everything is know except max $C_l$ (?)

@sophit Does this help?

Yes perfect. Now you can put everything in the last diagram (the one with the "takeoff parameter" - use the second equation for propeller aircraft) of this answer and you should get a good approximation. Obviously you have to use takeoff values, with $C_{l_{TO}}$ being $1.21 \times C_{l_{max}}$. $\sigma$ is the density ratio in respect to ISA sea level.

Are you planning to bet your life on an answer from ASE ; )


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Roller Coaster Airline
Could an airliner legally (using a common regional jets or less likely airliners) and safely perform acrobatic maneuvers that would otherwise not be permitted for commercial passenger flights. Why? For thrill seeking passengers. I enjoy turbulence, so maybe others may pay a little more for a short roller coaster flight. Is there a guide book of commercial aircraft acrobatic limitations and thresholds and special instruction on how to fly inverted, barrel rolls, stall recovery, and so forth?

What about zero-g flights? https://www.airzerog.com/ offers them for 6,000 or 8,000 € in their Airbus A310 Zero-G.

See this question; it may answer some of your points

Why in the world would you want to do aerobatics in an airliner? Their roll rates are slow, you can't see out much, they'd be very unexciting compared to airplanes designed for it. If you like turbulence fly commercial into Memphis International in July, you'll get plenty.

I can do zero G bunts in my plane but can only sustain it for about 3-4 seconds :(.

@wbeard52 You're looking for a new version of the old fashioned barn-stormer ride. I believe that there are 2-seat aerobatic-certified aircraft. All you need to do is find one with a pilot that offers rides. It's a "commercial" aircraft in that it takes paying passengers, but it's certainly not an "airliner".

This historic example seems relevant https://www.seattletimes.com/seattle-news/60-years-ago-the-famous-boeing-707-barrel-roll-over-lake-washington/

This is the nearest you will get to aerobatics. You can check out their website for more information.

Company History
After 11 years of surmounting meticulous procedures and safety
regulations, co-founders Dr. Peter H. Diamandis, veteran astronaut Dr.
Byron K. Lichtenberg and NASA engineer Ray Cronise acquired FAA
approval for G-FORCE ONE, a specially modified Boeing 727-200, to take
passengers on commercial parabolic flights. In August 2004, ZERO-G
flew its first commercial flight operating under the same safety
standards of all major air carriers and established its place into the
extreme tourism industry as the first and only commercial Zero Gravity
flight for the general public.
Additionally, in April 2006, ZERO-G became the first commercial
company to gain permission from the Kennedy Space Center to use the
shuttle runway and landing facilities to operate its weightlessness
flights.
ZERO-G has provided thousands of individuals the opportunity to
experience weightlessness including clients Stephen Hawking, Martha
Stewart and Buzz Aldrin.
ZERO-G not only caters to private clients but various organizations as
well. For example, National Geographic, Nick News and Discovery
Channel have all flown on G-FORCE ONE.
ZERO-G has also been featured on NBC’s The Today Show, Biggest Loser
and The Apprentice.
Apart from commercial flights, ZERO-G also provides research and
educational flights.

I am unaware of any passenger carrying jets that allow aerobatic maneuvers.  The reason is that these airplanes are built to haul a lot of passengers and baggage (payload).  The amount of structural reinforcement required to sustained six Gs would make it impractical to carry out its primary mission.

It would not have to be every flight or so intensive, Maybe a 15 minuted joyride before landing from a to b on a common 30 to 1 hour flight. I am interested in the legality of it. And thank you for answering promply.

All of the jets that I fly have a limitation of no aerobatics.

Is that limited by company policy or FAA?

The FAA.  It is most likely in section one of the AFM which is approved by the FAA.

@Justintimeforfun It wouldn’t matter how long. All planes are certified to certain limits, and it is illegal to intentionally exceed those limits at all. No company making airliners is going to spend billions to develop and certify one plane with higher limits than required for the mass market. And it’s illegal to use non-certified planes to carry passengers or cargo for hire.

So the new question should be" what maneuver could performed whilst staying within those certain limits?

Why does it have to be a commercial airplane?  There are companies willing to do aerobatic maneuvers in small airplanes for passengers.

Commercial aircraft are designed to be as lightweight and hence cheap to operate as possible. The aerodynamic and inertial loads of aerobatic manoeuvres demand stronger, heavier, less economic construction.
Even military types such as bombers often baulk at outright aerobatics; a bit of ducking and diving is about it, and even then that can shorten the airframe life. The Avro Vulcan was the first heavy bomber ever to loop the loop and it has seldom been emulated since.
If you want to fly aerobatics, join a flying club which has specialist aircraft to hand - and don't imagine you can take any luggage up with you.


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Are there any spark plug modifications that prevent fouling?
Today, the plane I had, failed the Run up because the magneto test failed. One of the spark plugs fouled out.
Other than making sure the engine is properly leaned out (even then spark plugs in a plane foul out more regularly than a car), what can be done mechanically to the spark plug? Like using non foulers or a spark plug alternative?

Lean it on the ground too.

What aircraft? What engine?

You mean modifications that haven't already been applied to the design?

I am still looking for a fix or alternative.

The plug fouling problem that afflicts most of the GA fleet, in good running engines, isn't carbon buildup or other gunk; it's tetraethyl lead in the fuel that sort-of condenses out of the fuel charge into liquid lead droplets, like condensing water in a glass, that hardens into little lead beads sticking to the plugs.
Some of the the tiny lead beads fall into the insulator well of the lower plugs, like dropping rocks into a pit, collecting at the bottom and piling up until they reduce the insulation path down the center electrode and the plug starts to short out (like the guy you threw into the bottom of the pit was able to climb out because of the pile of rocks you made throwing them into the pit at him).
The problem is the combustion temperatures of engines with lower compression ratios aren't high enough to keep all lead in a vapour state through the combustion.  100LL Avgas has a scavenging agent that is supposed to prevent this, but it isn't completely effective if the plug surface temperatures get too cool (Closed throttle idling is the worst time for this - airplanes that spends many minutes idling in long taxiway lineups are most effected. Carbureted engines are also more effected because of the less even fuel distribution and the richest cylinders will foul most).
Beyond the leaning procedures on the ground and in the air and avoiding extended close throttle idle, there isn't a physical mod to deal with lead formation on plugs other than making sure the plug's heat range is correct for the engine (if your engine is approved for the Champion RHM 37BY, a plug specially developed to reduce lead fouling in the Lyc O-235 for the Cessna 152, that could help), but if you are using avgas you can use ALCOR TCP additive to the fuel, which supplements the scavenging effect of the existing scavenging agent.
TCP was developed because the same thing was a big problem on the B-36 bomber using 115/145 octane avgas (which had crazy lead levels to get that octane rating) and lead fouling of the bazillion cylinders in all those engines on the very long cruise flights, at low power settings that that bomber could do, was a big tactical problem.
You have to mix the TCP into the fuel when you refuel, using a graduated syringe (I used to tow gliders in a Cessna L-19, which has a low compression Cont O-470, and the club used it for a while before deciding the hassles were too much with all the mixing and injecting at every refueling, and gave up).  A lot of owners can't be bothered with the hassle and expense and just go with elaborate leaning techniques to minimize the problem, and pull the lower plugs to clean them off from time to time.
Interesting aside: I learned a while back that the active ingredient in TCP, tri-cresyl-phosphate, just happens to be the same stuff that Lycoming told owners to put in the oil on the O-320 AD engines that had the cam spalling crisis back in the 80s. In the oil it acts as an anti-scuffing agent, providing initial lubrication when the parts are oil starved at startup. It's also an additive to the Aero Shell semi-synthetic engine oil line.
The other (better) solution is to run the plane on unleaded mogas, which is what I do.  My Lycoming O-290, with only about a 7.5:1 compression ratio, does NOT like avgas and fouls the lower plugs in only about 25 hours even with religious leaning.  On Mogas it is happy as a clam and I only ever see a light soot coating on the plugs at annual.

Downvote because fouling can be caused by many factors, including carbon contrary to your answer. Common types of fouling include lead, carbon, silica, loose debris, and oil. Another common cause of spark plug failure is a cracked ceramic insulator. I have dealt all of these as a mechanic. Lead fouling is one of the most commonly encountered in an otherwise well-running engine, as you highlight.

I'm assuming an engine is in good condition and discounting mechanical defects because the OP is looking for a solution to the overall GA fleet problem of lead fouling, which is 99% of the issue on engines that aren't pumping oil.  When you run on mogas, which makes a lot more soot than avgas, plug fouling on a jug that isn't pumping oil through is almost unheard of.  My O-290 has fairly high oil consumption, about a qt in 4-5 hrs, and even at that level I don't have oil fouling issues and on mogas there is only trace carbon buildup.  If I run on 100LL, it quickly becomes a mess from lead.

@JohnK yes 100 hour inspection etc.

@Justintimeforfun I added an edit to mention a fouling resistant plug that Champion makes for the O-235 that is apparently approved for various engines now.  Something to look into.

@JohnK You're right, in good condition operating in most parts of the US the lead fouling is going to be the biggest issue. I flew an O-320 a little over 1000 hrs and didn't have a single fouled plug. Operated on a combination of 100LL and 91UL. No difference regardless of fuel type. Oil changes once a week (every 30-50 hrs) and carbon was normal. Ran that engine pretty lean. I operated an older O-320 a little and had multiple carbon fouling incidents, not soot, but loose bits of carbon/debris. I used to work on pistons flying in the desert and silica fouling was the biggest problem there.

@JWalters yeah the silica, to the extent it gets past the air filter, turns the oil into lapping compound. I'll bet that the silica fouling comes mostly from silica suspended in the oil.  The CF-34 turbo fans in the CRJs, in North African and Iraqi desert airline operations, found their engines wearing out in about 1/3rd normal life just from turbine erosion from the talc-like sand.  There was a big effort to get them to use flex thrust for take off, which helps a lot, but the capts there just wouldn't use it and went balls to the wall every takeoff and engines were shot after 5000 hrs.

As Ron notes in the comments
Lean your engine on the ground

Proper leaning during idle and taxi operations is much more important than most pilots understand. It can solve spark plug fouling problems, reduce valve guide wear and valve sticking problems, and prolong engine life.
Mixture distribution is poor at idle. At a rich idle mixture, some fuel doesn’t vaporize and enters the cylinder as a liquid where it partially burns and forms carbon deposits.
In addition, a rich idle mixture causes lead fouling. Since
gasoline, tetraethyl lead (the octane enhancer in avgas), and ethylene dibromide (the lead scavenging agent in avgas) all have different boiling points, fractionalization occurs in the induction pipes. Some cylinders get a high dose of lead with no lead scavenger while other cylinders get the scavenger but with little lead.

Or better yet have your mechanic make sure its set up correctly

Rather than manually leaning your engine for ground operations, it’s better to have your mechanic adjust the idle mixture to a properly lean setting. If you lean manually on the ground, you need to understand the risks.

I agree it's a good practice, but this doesn't answer the question which is about spark plugs.

If you mech adjust the fueling to lean, you lose the full mixture adjust range. I strongly advice against this practise. At full rich setting, your engine is supposed to run rich, not at optimal lean!

WRT having your mechanic adjust the idle mixture, how?  Airports are at different elevations, so the proper lean mixture is going to be different.  If your home field is say Truckee at 5900 ft, and mixture is set for it, you'll be running quite lean if you fly to anywhere along the coast or in the Central Valley.

I believe the intention of the note in the article is that your mixture should be adjusted properly so that lean on the adjuster is sufficiently lean and rich is not overly rich (i.e. your range of adjustment is proper)

The mixture is adjusted properly when full lean is too lean, and full rich is too rich  but yea, i get the point. Correctly adjusted engine will foul pulgs when run full rich on ground, no getting around that. That's how they are.

If there were a design change that would prevent fouling, it would be standard by now.
However, the way you operate the plane can prevent or at least reduce fouling, i.e.  leaning the mixture properly for taxi and cruise. In most cases, leaning for taxi will clean the plugs enough by the time you get to the run-up area that you’ll pass a mag check.
If not, particularly in flight school planes that spend an abnormally large fraction of their time at a full-rich mixture (for pattern work), you can clean the plugs by leaning the mixture and running the plane at the run-up power setting for a few minutes. Do the mag check again at full rich (or as needed for altitude), and you should pass.

I have to disagree.  Design changes and GA engines just don't go together.  There IS a design change that seems to have virtually eliminated plug fouling in automotive engines: EFI and associated automatic mixture controls.  In the old carburetor days, it was normal to clean and/or replace plugs at 10-20K miles; nowadays 100K isn't unusual.

@jamesqf very good point!!!

@jamesqf Some GA piston planes now come with a FADEC that eliminates the mixture and prop controls, but the cost to develop an STC for retrofits would be prohibitive, and most pilots are too cheap to buy it anyway.

@StephenS: Yes, which is why design changes and GA engines just don't go together.


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When do flights get cancelled due to fog?
When flights get cancelled due to fog, what triggers the cancellation? Fog is too thick, too wide-spread, blocks the view of tall buildings or other landmarks? Or is the problem the type of air traffic? Too many helicopters or small-ish aircraft?

Other answers have addressed the case of weather that's too bad for flights to operate, but another situation that can occur is congestion.
Take a look at the Average Arrival Rate chart for San Francisco International Airport (SFO) (more details on this in this blog post by an airline dispatcher). During visual conditions with favorable winds, they can operate in normal flow and accept 54+ arrivals/hour into two parallel runways, with departures using the perpendicular runways in between arrivals. But that only works when the cloud ceilings are above 3,000-3,500ft. That procedure relies on aircraft being able to visually see and avoid each other when flying in close proximity.
If there's fog (or low stratus clouds that don't touch the ground, as is typical), that can't happen; you can't send jets blindly into a cloud 750 feet apart from each other. If the clouds are high enough (per the chart, a minimum ceiling of 1,600ft and 4mi visibility), they can use a special SOIA procedure (Simultaneous Offset  Instrument  Approach)—essentially a guided, monitored way to direct jets into a cloud 2,000 feet apart—and accept around 36 arrivals/hour. And if the weather is too poor for that, the average arrival rate can drop to 25 arrivals/hour or below. The extra procedures and spacing required to safely manage traffic in the weather reduces the airport's capacity.
When this happens, there's nothing that stops any specific commercial flight from using the airport—they all have the necessary technology to land in most cloudy conditions—, but the airport's capacity is now too low to accommodate everyone. The FAA will impose a ground delay program to meter traffic into the airport until conditions improve (otherwise you end up with too many flights circling and diverting to other airports, causing many other problems), and the result is flight delays and cancellations.

For landing aircraft, the Instrument Approach Procedures available will dictate the required ceiling (height of clouds above ground) and visibility (horizontal). The most common approach type for airlines is an Instrument Landing System (ILS).
ILS Category I requires a ceiling of at least 200 feet and visibility of at least 1800 feet. With special equipment on the ground and in the plane plus specially trained crews, this can be improved to Category II at 100/1200, Category IIIA at 50/700, or Category IIIB at 50/300. "Fog" is defined as a cloud at ground level, though, so these requirements still wouldn't be met.
ILS Category IIIC theoretically allows landing with 0/0, but the standard has never been implemented and will probably be rescinded.
If the weather doesn't meet the minima for any approach procedure, arriving aircraft cannot legally land and must divert elsewhere. If such conditions are forecast for when they plan to arrive, there is also likely to be a ground delay program that prevents them from even taking off.
For departing aircraft, airlines are not allowed to take off from an airport where they cannot legally land in the event a problem forces them to return. Private pilots are allowed to do so, but few will unless they know the fog is localized, which is common in coastal areas.

Would you be able to add examples of limits for ILS Cat II/III? I think that'd be helpful context for this answer :)

@JeffBridgman Done.

At bigger airports when it's foggy, the limits are set by light transmissiometers along the runway that measure the horizontal visibility, giving a value called Runway Visual Range (RVR).  You follow Low Visibility departure procedures, which include minimum RVR requirements as well as certain runway lighting requirements, departure alternate airport requirements (because you can't return to that airport to land if something goes bad on the departure) etc, that have to be met.
So if the departure is cancelled due to fog, it's probably because the RVR is too low (too foggy along the runway itself) for whatever procedure the crew is qualified for.  Or the available runway doesn't have the low vis equipment requirements.  Or there is no usable departure alternate airport.
Or the departure may also be cancelled due to fog forecast at the destination.